Detection of Carbon Recombination Lines at Decameter Wavelengths in Some Galactic Objects
The recombination lines of highly excited carbon atoms near 25 MHz were detected in the directions of DR 21, S140 and L 1407. The line intensity is about 10-3 of the background level, with the width varying between and 8 KHz and the line of sight radial velocity close to zero. Evaluating the physical parameters of the medium responsible for line formation we have obtained the electron number density in DR 21 and S 140 below 1 cm-3. The estimate for the cloud L 1407 is, with allowance for the data on the background continuum absorbtion, 0.05 to 0.1 cm-3 with an electron temperature of 10 to 20 K. The highly sensetive techniques of decameter band radio spectroscopy suggest way of detecting low density cold interstellar plasmas with ionized carbon in various galactic objects.
KeywordsDust Cloud Recombination Line Antenna Beam Decameter Wavelength Galactic Background
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- Abramenkov, E.A. (1985) ‘Low frequency radio observations of HII regions: The galactic disk region 147° < 1 < 153° Sov. Astron.J., 62, 1057–1064.Google Scholar
- Falgarone, E. (1980) ‘Carbon and sulfure ionized regions in dark clouds’, in P.A. Shaver (ed.), Radio Recombination Lines, pp. 141–147.Google Scholar
- Konovalenko, A.A.(1984) ‘Detection of decameter wave radio lines of excited carbon in some galactic objects’, Sov. Astron. J. Lett., 10, 912–917.Google Scholar
- Konovalenko, A.A. ‘Review of decameter wave recombination lines: problems and methods’, this issue.Google Scholar